Communication system



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coax/AL uur: To mman' :mr/aus mmabzlmi Patented Apr, 12, 1949 g i UNITED s'raras niniflaa'r carica f -l Meernf istarai William M. Hall. Lexlnxton. Mass.. alxnor i Raytheon Manufacturing Company. VMass.,:scorporationotDelaware Y s Newton,

Continuation of apigplloatlon Serial No. 818,181.

This application December 23, 19H. Serial No. 793.453

September 24, 1945.

This invention relates to communication systems, and more particularly to a communication system which enables the transmission of electrical signals from a central station to a group of remote stations, and the transmission of electrical signals from any one oi said remote stations back to said centralstation. and to all of the other remote stations.

This application is a continuation of applicant's copending application entitled Communication Systems. Serial No. 618,181, nled September 24, 1945, now abandoned.

It is the main object-of the present invention to provide a communication system of the general character indicated ln which each of the branches thereof is so isolated from the remainder of the system that should a particular branch be rendered inoperative, the remainder of the system is unaffected, and can continue to function in a normal manner.

This, and other objects of the present invention, which will become more apparent as the detailed description thereof progresses, are attained, briefly, in the following manner:

There is provided a iirst group of switching devices, preferably of the electron-discharge type, for example, in the form oi cathode-follower ampliiiers, corresponding in number to the number of stations in the system. The input circuits of such devices are connected, in parallel, to a localsignal generator located at one oi' said stations, namely, at the central station.

There is pro' `ded a second group o! similar switching devices, corresponding in numbento one less than the number of stations in the system. the input circuits oi' said second group o! switching devices being connected to local-signal generators and signal receivers locatedY ai:A the various remote stations., 1

The output circuits of all but one' of tn e rst group of switching devices are connected. respectively. to the input circuits of said second group of switching devices, and are also connected, respectively. to the signal receivers at the remote stations, the output circuit of said one of said rst group oi switching devices being connected to a signal receiver located at the central station The output circuits of the second group of switching devic feed a common load which ls, in tum, connected oz-:ck to the inputcircuits of the first group of switching devices.

By means ci this system. signals originating at the central station are received there by the local 'receiver'. and at the remote stations as well; and

signals originating at any or' the remote stations are received hy'their local receivers, and at the.,

, z'- central station and remaining remote station: as well.

By using cathode followers in the circuit out lined, the various stations are so isolated with respect to all others that damage to any one is confined thereto. and does not interfere with con. tinued operation of the rest o! the system.

In the accompanying specification there shall be described. and in the annexed drawing shown, an illustrative embodiment of the communication system of the present invention. It is, however. to be clearly understood that the present invention is not to be limited tothe details herein shown and described for purposes of illustration only, inasmuch as changes therein may be made without the exercise of invention and within the true spirit and scope of the claims hereto ap. pended'.A

In said drawing, the single ligure is a partial block, partial schematic diagram o( a communication system assembled in accordance with the principles of the present invention.

Referring. now more in detail to the aforesaid illustrative embodiment oi' the present invention,

with particular reference to the drawing illustratlng the same, the numeral la designates a localslgnal generator located at a central station. the

,output of said local-signal generator being applied in parallel, to the grids IE to i9, inclusive, ot anrst connected to the above-mentioned B voltage group of vacuum tubes 20 to 23, inclusive, said tubes having cathodes 24 tu 21, inclusive, respectively connected, through resistors 28 to 3l, i'nclusivc. to ground. and anodes 32 to S5. inclusive,

The cathode output of the tube 20 is applied to a receiver 35 located at the central station and the cathode outputs of the tubes 2i to 23, inclusive, are respectively applied. through, for example, coaxial lines 31 to 39, inclusive, to remote reivers 43 to 62. inclusive. A

Thus, the signals originating at the central generator IB are applied, through the cathode icllower l2, to the cathode '.-iowers 29 to '23, Enola. sive. and, through the .en to the central and remote receivers B and e' 'to 2, inclusive.

Now as stated in earier portions oi this speel.

at the remote stations be received :it the central station and at thc other remote stations as well. For this purpose, the remote stations may be provided with signal generators i3 lo l5. inclusive, similar to the signal generator il The outputs of the signal generators 43 to l5, inclusive. may be respectively applied, through the coaxial cables 31 to 38, inclusive, to the grids 4S to 48, inclusive. of a second group oi vacuum tubes 45 to Si'inclusive, said tubes having cathodes 52 to5l. inclusive, connected, in parallel, to

the previously-mentioned resistor il, constituting u common load, and anodes 55 to `Sl inclusive,

connected to the previously referred to B voltage supply. It will thus be noted that the signals oi each of the remote stations appear across the common load resistor i4 and, therefore, are applied to the input circuits oi the tubes to 23, inclusive. Hence.. these signals appear at the central receiver 3G. and also, at the receivers 4D to L2, inclusive. at each ot the remote stations.

This completes thc description of the aforesaid illustrative embodiment ot the present invention. It will be noted from all of the foregoing that by means oi'the present invention two-way communication may be established between a plurality oi separated stations. while at the same time said stations are so isolated with respect to each other that a. failure at one has no effect upon the remainder, thereby enabling continued operation of the system among said remain;"er.

Other objects and advantages of the present invention will readily occur to those skilled in the art to which the same relates.

l u il the remainder of said stations; all but one of said first group ot' switching devices having output circuits connected, respectively, to the input circuits of said second group ot' switching devices, and also connected, respectively, to the signal receivers of said remainder of said stations; said one ot said iirst. group of switching devices having an output circuit connected only to the signal receiver of said first ot said stations and said second group oi switching devices having a common output circuit connected to the input circuits o! said nrst group of switching devices.

2. 1n a system for intercommunication between a plurality ot stations each ot which includes a signal source and a signal receiver, the combination ol a first group of electron-discharge devices. corresponding in number to the number of said stations, and having input circuits connected, in parallel. to the signal source of a first o! said stations; a second group of electron-discharge devices, corresponding in number to one less than the number of said stations. and having input circuits connected. respectively, to the signal sources ol the remainder of said stations; all but one of said rst group of electron-discharge devices having output circuits connected. respectively, to the input circuits of said second group of electrondischarge devices. and also connected, respectively. to the signal receivers of said remainder of said stations: said one of said first group of electron-discharge devices having an output circuit connected only to the signal receiver oi' said rst ol said stations and said second group of electron-discharge devices having a. common output circuit connected to the input circuits of said rst group oi electron-discharge devices.

3. In a system for intercommunicatlon between a plurality of stations each of which includes a signal source and a signal receiver, the combination of a rst group oi cathode-follower amplifiers, correspondin, in number to the number of said stations, and having input circuits connected, in parallel, to the signal source of a rst of said stations; a second group of cathode-follower amplifiers, corresponding in number to one less than the number of said stations', and having input circuits connected. respectively, to the signal sources of the remainder oi' said stations;l all but one of said rst group ot cathode-follower amplitiers having output circuits connected, respec-v tively. to the input circuits of said second group of cathode-follower amplifiers, and also connected, respectively, to the signal receivers ot said remainder oi said stations; said one of said rst group of cathode-follower amplifiers having an output circuit connected only to the signal receiver of said first of said stations and said second group of cathode-follower amplifiers havlng a common output circuit connected to the input circuits of said rst group o1' cathode-follower ampliiiers.

WILLIAM M, HAIL.

No references cited. 

